The invention relates to an infrared seeker head for a missile, and to an infrared optical device on a launcher tube for the missile, for combatting flying targets.
Infrared (IR) seeker heads are known for man portable air defense systems or air-to-air missiles, in which the flying targets must be detected by the gunner's eyes--with or without the assistance of visual aids or heat imaging apparatuses. In such weapons the whole missile with the seeker head must be visually aligned with the target so that the target is in the visual field of the seeker head, which measures only a few degrees. When the seeker head is locked onto the target assigned to it in this manner, the combat operation can start.
It is a disadvantage of such seeker heads that the gunner must visually detect the target with his eyes, because this requirement results in very short detection distances, which are even lower when the visibility is poor. Generally, there is no night combat capability at all. Even if a heat image apparatus is available to the gunner, it is difficult to align the missile so that the seeker head also has the target within the small visual field, because of the parallax problem.
Seeker heads are also known in which the visual field is set by means of a relatively smaller instantaneous visual field which scans the whole visual field. These seeker heads have the disadvantage that they can implement relatively short lock-on distances because the radiation of the target falls onto the detector or the detector array in only a fraction of the time--specifically when sweeping over the target.
Scanning seeker heads of the above-mentioned type are also known which use certain logic in the target tracking operation in order to avoid being deflected from the target by false infrared targets, such as flares. However, newly developed flares, and/or the quantity of the flares which are ejected simultaneously (or in short succession), can cause such logic to fail so that the seeker head is deflected from the real target.
It is an object of the invention to provide a seeker head which can detect flying targets at large distances, at night and in poor visibility.
Another object of the invention is to provide a seeker head which can identify the type of flying target at long distances.
Still another object of the invention is to provide a seeker head which can lock onto flying targets for long distances, which cannot be deflected by false IR targets.
These and other objects and advantages are achieved by the optical system according to the invention, in which the missile itself has an infrared seeker head which includes a viewing lens system and a focal plane array on which the visual field of the lens system is focussed. The image acquired by the focal plane array is displayed on a video display unit. Mounted on the missile launch tube in the beam path of the seeker head viewing lens system is a wide angle lens, which can be retracted to remove it from the seeker head beam path. The wide angle lens enables the gunner to view a large visual field initially. Then, when a "suspicious" object is detected, it can be removed out of the beam path after moving the missile in the direction of this object to allow a positive identification of the type of target. A pair of rotating optical wedges are disposed in the beam path of the seeker head, so that its relatively smaller visual field can be diverted to compensate for maneuvering of the target.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.